In a process of continuously casting metal strips such as ribbons, it is common practice to dispense the molten metal through a nozzle onto a moving chilled substrate. The molten metal solidifies soon after contact with the chilled substrate. A cast product having an amorphous molecular structure, in the form of a relatively thin elongated strip or ribbon, has proven to be effective for winding into highly efficient cores of electrical transformers, and other uses. Recent developments in the casting of amorphous metal strips are reviewed in U.S. Pat. No. 4,332,848.
The width of a cast ribbon is generally a function of the longitudinal dimension of a dispensing slot in the nozzle. In the past, ribbons have been cast to a width desired for end use. When a different width is desired, the nozzle is replaced with another nozzle having a dispensing slot of the desired length. Changing nozzles has many disadvantages. Most importantly, the molten metal in the nozzle and the crucible reservoir must be removed and the entire unit cooled causing substantial loss of valuable casting time and several man-hours of labor. Also, a large inventory of nozzles with different slot lengths must be maintained adding to the capital cost of the casting operation. Further, even when nozzles are changed, precision control over ribbon width is difficult to establish and maintain. Although there has been some progress in providing nozzles with movable elements to vary the width of the cast ribbon, such as shown in copending application, Apparatus for Adjustably Controlling the Width of a Cast Metal Ribbon, Ser. No. 482,981, filed Apr. 7, 1983 and assigned to the present assignee, it is still difficult to vary the ribbon width with these devices without stopping the casting assembly.
Relatively narrow ribbons are required for many applications. In the past, these narrow ribbons have generally been formed on the same casting surfaces as wide ribbons. The dispensing nozzle is simply replaced by a nozzle having a shortened discharge orifice corresponding to the width, as noted above. In such circumstances, much of the capacity of the casting assembly goes unused. Further, it has been necessary to individually wind each narrow ribbon with winding equipment.